// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (C) ST-Ericsson SA 2011
   *
   * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.

   */
  
  #include <linux/sysfs.h>

  #include <linux/init.h>
  #include <linux/stat.h>
  #include <linux/slab.h>
  #include <linux/idr.h>
  #include <linux/spinlock.h>
  #include <linux/sys_soc.h>
  #include <linux/err.h>

  #include <linux/glob.h>

  static DEFINE_IDA(soc_ida);

  /* Prototype to allow declarations of DEVICE_ATTR(<foo>) before soc_info_show */
  static ssize_t soc_info_show(struct device *dev, struct device_attribute *attr,
  			     char *buf);

  
  struct soc_device {
  	struct device dev;
  	struct soc_device_attribute *attr;
  	int soc_dev_num;
  };
  
  static struct bus_type soc_bus_type = {
  	.name  = "soc",
  };

  static DEVICE_ATTR(machine,		0444, soc_info_show,  NULL);
  static DEVICE_ATTR(family,		0444, soc_info_show,  NULL);
  static DEVICE_ATTR(serial_number,	0444, soc_info_show,  NULL);
  static DEVICE_ATTR(soc_id,		0444, soc_info_show,  NULL);
  static DEVICE_ATTR(revision,		0444, soc_info_show,  NULL);

  
  struct device *soc_device_to_device(struct soc_device *soc_dev)
  {
  	return &soc_dev->dev;
  }

  static umode_t soc_attribute_mode(struct kobject *kobj,

  				struct attribute *attr,
  				int index)

  {

  	struct device *dev = kobj_to_dev(kobj);

  	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

  	if ((attr == &dev_attr_machine.attr) && soc_dev->attr->machine)

  		return attr->mode;

  	if ((attr == &dev_attr_family.attr) && soc_dev->attr->family)

  		return attr->mode;

  	if ((attr == &dev_attr_revision.attr) && soc_dev->attr->revision)

  		return attr->mode;

  	if ((attr == &dev_attr_serial_number.attr) && soc_dev->attr->serial_number)

  		return attr->mode;

  	if ((attr == &dev_attr_soc_id.attr) && soc_dev->attr->soc_id)

  		return attr->mode;

  	/* Unknown or unfilled attribute */

  	return 0;
  }

  static ssize_t soc_info_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)

  {
  	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

  	const char *output;

  
  	if (attr == &dev_attr_machine)

  		output = soc_dev->attr->machine;
  	else if (attr == &dev_attr_family)
  		output = soc_dev->attr->family;
  	else if (attr == &dev_attr_revision)
  		output = soc_dev->attr->revision;
  	else if (attr == &dev_attr_serial_number)
  		output = soc_dev->attr->serial_number;
  	else if (attr == &dev_attr_soc_id)
  		output = soc_dev->attr->soc_id;
  	else
  		return -EINVAL;
  
  	return sysfs_emit(buf, "%s
  ", output);

  }
  
  static struct attribute *soc_attr[] = {
  	&dev_attr_machine.attr,
  	&dev_attr_family.attr,

  	&dev_attr_serial_number.attr,

  	&dev_attr_soc_id.attr,
  	&dev_attr_revision.attr,
  	NULL,
  };
  
  static const struct attribute_group soc_attr_group = {
  	.attrs = soc_attr,
  	.is_visible = soc_attribute_mode,
  };

  static void soc_release(struct device *dev)
  {
  	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);

  	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
  	kfree(soc_dev->dev.groups);

  	kfree(soc_dev);
  }

  static struct soc_device_attribute *early_soc_dev_attr;

  struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
  {
  	struct soc_device *soc_dev;

  	const struct attribute_group **soc_attr_groups;

  	int ret;

  	if (!soc_bus_type.p) {

  		if (early_soc_dev_attr)
  			return ERR_PTR(-EBUSY);
  		early_soc_dev_attr = soc_dev_attr;
  		return NULL;

  	}

  	soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
  	if (!soc_dev) {

  		ret = -ENOMEM;

  		goto out1;
  	}

  	soc_attr_groups = kcalloc(3, sizeof(*soc_attr_groups), GFP_KERNEL);
  	if (!soc_attr_groups) {
  		ret = -ENOMEM;
  		goto out2;
  	}
  	soc_attr_groups[0] = &soc_attr_group;
  	soc_attr_groups[1] = soc_dev_attr->custom_attr_group;

  	/* Fetch a unique (reclaimable) SOC ID. */

  	ret = ida_simple_get(&soc_ida, 0, 0, GFP_KERNEL);
  	if (ret < 0)

  		goto out3;

  	soc_dev->soc_dev_num = ret;

  
  	soc_dev->attr = soc_dev_attr;
  	soc_dev->dev.bus = &soc_bus_type;
  	soc_dev->dev.groups = soc_attr_groups;
  	soc_dev->dev.release = soc_release;
  
  	dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);
  
  	ret = device_register(&soc_dev->dev);

  	if (ret) {
  		put_device(&soc_dev->dev);
  		return ERR_PTR(ret);
  	}

  
  	return soc_dev;
  
  out3:

  	kfree(soc_attr_groups);

  out2:
  	kfree(soc_dev);
  out1:
  	return ERR_PTR(ret);
  }

  EXPORT_SYMBOL_GPL(soc_device_register);

  
  /* Ensure soc_dev->attr is freed prior to calling soc_device_unregister. */
  void soc_device_unregister(struct soc_device *soc_dev)
  {

  	device_unregister(&soc_dev->dev);

  	early_soc_dev_attr = NULL;

  }

  EXPORT_SYMBOL_GPL(soc_device_unregister);

  
  static int __init soc_bus_register(void)
  {

  	int ret;

  	ret = bus_register(&soc_bus_type);
  	if (ret)
  		return ret;
  
  	if (early_soc_dev_attr)
  		return PTR_ERR(soc_device_register(early_soc_dev_attr));
  
  	return 0;

  }
  core_initcall(soc_bus_register);

  static int soc_device_match_attr(const struct soc_device_attribute *attr,
  				 const struct soc_device_attribute *match)

  {

  	if (match->machine &&

  	    (!attr->machine || !glob_match(match->machine, attr->machine)))

  		return 0;
  
  	if (match->family &&

  	    (!attr->family || !glob_match(match->family, attr->family)))

  		return 0;
  
  	if (match->revision &&

  	    (!attr->revision || !glob_match(match->revision, attr->revision)))

  		return 0;
  
  	if (match->soc_id &&

  	    (!attr->soc_id || !glob_match(match->soc_id, attr->soc_id)))

  		return 0;
  
  	return 1;
  }

  static int soc_device_match_one(struct device *dev, void *arg)
  {
  	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
  
  	return soc_device_match_attr(soc_dev->attr, arg);
  }

  /*
   * soc_device_match - identify the SoC in the machine
   * @matches: zero-terminated array of possible matches
   *
   * returns the first matching entry of the argument array, or NULL
   * if none of them match.
   *
   * This function is meant as a helper in place of of_match_node()
   * in cases where either no device tree is available or the information
   * in a device node is insufficient to identify a particular variant
   * by its compatible strings or other properties. For new devices,
   * the DT binding should always provide unique compatible strings
   * that allow the use of of_match_node() instead.
   *
   * The calling function can use the .data entry of the
   * soc_device_attribute to pass a structure or function pointer for
   * each entry.
   */
  const struct soc_device_attribute *soc_device_match(
  	const struct soc_device_attribute *matches)
  {
  	int ret = 0;
  
  	if (!matches)
  		return NULL;
  
  	while (!ret) {
  		if (!(matches->machine || matches->family ||
  		      matches->revision || matches->soc_id))
  			break;
  		ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches,
  				       soc_device_match_one);

  		if (ret < 0 && early_soc_dev_attr)
  			ret = soc_device_match_attr(early_soc_dev_attr,
  						    matches);

  		if (ret < 0)
  			return NULL;

  		if (!ret)
  			matches++;
  		else
  			return matches;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(soc_device_match);